Generally, a key assembly for operating a car engine by a user is arranged inside a car, and, if an operating key is inserted into the key assembly and rotated, the engine starts to operate. Recently, it is possible to operate an engine simply by pressing a start button provided inside the car, without using the operating key.
Due to development of communication technologies, a so-called smart key system has been introduced which is designed to improve user convenience and prevent car theft and which works such that a user having a smart key performs encrypted wireless communication with an Electronic Control Unit (ECU) installed in a vehicle and only an allowed user is able to operate the engine of the car.
The smart key system is a developed version of a car lockset for preventing car theft, and the smart key system works such that a smart key for starting a car wirelessly generates an encrypted code, and a car engine starts to operate only when the ECU determines that the encrypted code conforms to a set code.
That is, the smart key system is an anti-theft system in which a car engine is allowed to start using a start button only when a driver having the smart key is at least in proximity where communication with the ECU is possible, so that it is possible to prevent a non-allowed user from robbing the car.
A slim smart card key used in a smart key system of a related art is generally large in size and not convenient to carry. In addition, in a case where the smart key is reduced in size, an additional function other than a user authentication function cannot be applied, and thus, this is the reason that it is difficult to make the card key thin.
These days, the smart key is tends to be made as a thin card key for wallet carrying, but, if the smart key decreases in thickness to be thin, it may degrade hardness and the smart key may be easily damaged by a physical frictional force within a wallet.
In particular, a wireless communication device has to include a spare key receiving part for receiving a spare key that is used in an emergency situation where the smart key system is unable to work for some reasons, including battery discharge of a smart key. If this spare key receiving part is made of an epoxy molding material, a spare key settling part of a steel material different from the epox molding material should be provided to prevent damage led by a physical contact with the spare key.
Before the spare key receiving part is formed using the epoxy molding material, the spare key settling part needs to be fixed on to a Printed Circuit Board (PCB), and it may make the manufacturing process complicated.
In addition, since the smart key needs to be made thin, it is difficult to form a switch unit which is able to transmit an active entrance signal for locking or unlocking a car door as a user actively applies the signal at a remote location.